ER6--Drag It To The Robot!

ERb Clean-up

Let's talk about this common response:

• "B is correct because the concrete and water bond which is a chemical change, and can not be reversed. And C is also right because after smelting iron ore, it can not be reversed as well."

Reversibility is NOT the key marker here! You should NOT rely on reversibility in your answer. Consider this:

• "Lime, the First Cement
• "Lime is a substance used since ancient times to make useful things like plaster and mortar. Lime is made by burning, or calcining, limestone—and that's how limestone gets its name. Chemically, lime is calcium oxide (CaO) and is made by roasting calcite (CaCO3) to drive off carbon dioxide (CO2). That CO2, a greenhouse gas, is produced in great quantities by the cement industry.
• "Lime is also called quicklime or calx (from Latin, where we also get the word calcium). In old murder mysteries, quicklime is sprinkled on victims to dissolve their bodies because it is very caustic.
• "Mixed with water, lime slowly turns into the mineral portlandite in the reaction CaO + H2O = Ca(OH)2. Lime is generally slaked, that is, mixed with an excess of water so it stays fluid. Slaked lime continues to harden over a period of weeks. Mixed with sand and other ingredients, slaked lime cement can be packed between stones or bricks in a wall (as mortar) or spread over the surface of a wall (as render or plaster). There, over the next several weeks or longer, it reacts with CO2 in the air to form calcite again—artificial limestone!"
  • source: http://geology.about.com/od/mineral_resources/a/cement.htm

Check your Gaggle for feedback, and send me an analysis of you incorrect answer, if necessary!

ERc: Polymers

Please follow the link for your third benchmark assessment of the chapter!

Windmills

You'll have a chance to try your hand at windmill design, and we'll test out the voltage you are able to produce!